Purpose: The cross-protection of 7-valent pneumococcal conjugate vaccine (PCV7) against vaccine-related serotypes has been controversial. We investigated the serological properties of cross-protective antibodies against vaccine-related serotypes 6A, 6C, and 19A induced in young children aged 12-23 months after booster immunization of PCV7. Methods: IgG and IgM antibody concentrations and opsonic index (OI) against vaccine serotypes 6B and 19F and vaccine-related serotypes 6A, 6C, and 19A were measured by ELISA and opsonophagocytic killing assay (OPA) in 4 selected immunesera. The serological properties and antigenic specificity of protective antibodies were determined by IgM depletion of immunesera, OPA, and competitive OPA against serogroup 6 and 19 pneumococci. Results: Compared to pre-IgM depleted immunesera, OI of IgM-depleted immunesera against 6B and 19F decreased and OI against 6A, 6C, and 19A decreased, too. In competition OPA, free 6B and 19F polysaccharide completely inhibited the immune protection against vaccine-related serotypes 6A, 6C, and 19A as well as vaccine types 6B and 19F. Conclusions: The booster immunization of PCV7 certainly induced cross-protective antibodies against vaccine-related serotypes 6A, 6C, and 19A with both IgG and IgM isotypes. Furthermore, IgM antibodies are more highly contributed to opsonophagocytic activity against vaccine-related serotypes as well as most of vaccine types than do IgG antibodies. Further studies are needed for the more immunized sera in the children as well as adults.

Purpose : This study aimed to explore how prevalent the community-related methicillin-resistant Staphylococcus aureus (CA-MRSA) was in children with muscular-skeletal infections. Methods : We retrospectively reviewed the medical records of patients of 18 years or under who were diagnosed with suppurative arthritis or osteomyelitis and S. aureus from September 2000 through August 2012 at the CHA Bundang Medical center. Results : Thirty-one cases of suppurative arthritis or osteomyelitis were identified. The patients were between 17 days old and 18 years old with an average age of 7. Eleven cases (33.5%) of suppurative arthritis and 16 cases (51.6%) of osteomyelitis were observed. Five cases were accompanied by the two diseases. Methicillin sensitive S. aureus (MSSA) was isolated in 25 cases (80.6%) and methicillin resistant S. aureus (MRSA) was isolated in 6 cases (19.4%). Multidrug resistant strains were not observed. MRSA was not found from 2000 through 2005. All patients were treated with antibiotics and the duration of antibiotics treatment was days. Vancomycin was used as the initial antibiotic treatment in 4 cases (12.9%) and vancomycin was used as the definitive antibiotics in the 10 cases (32.3%). Conclusions : The result of this study showed that methicillin resistance rate of S. aureus from muscular-skeletal infections was concentrated in the latter half of the 12 year period.

Objectives: Outbreaks of pneumonia caused by Mycoplasma pneumoniae (MP) occur every 3-4 years in Korea, most recently in 2011. The aim of our study was to determine the optimal time to perform indirect particle agglutination antibody assays to improve early diagnosis of MP pneumonia in children. Methods: A database of 206 pediatric patients treated for pneumonia at the Hanyang University Hospital from June to October 2011 was analyzed retrospectively for demographic characteristics and laboratory test results. Results: Among the 206 patients treated for pneumonia during the study period, there were 160 children (mean age, 5.44 years) diagnosed with MP pneumonia, who were studied further. The mean age of these MP pneumonia patients was 5.44 years. Antibody titers increased with increasing time between symptom onset and the collection of serum collection: MP titers were <1:640 for sera collected after 5.44 days and titers for those collected after 8.58 days; P<0.001). Antibody titers were considered positive when they reached . In 42 MP pneumonia patients in whom there was a four-fold or greater increase in titer between successive serum samples, the optimal cut-off time-point for distinguishing between the initial and second titer groups was 7.5 days after the onset of symptoms (sensitivity, 90.5%; specificity, 92.9%). Conclusions: Negative MP antibody titers earlier than 8 days after the onset of symptoms in children with pneumonia may require repeating to confirm the diagnosis. This finding could optimize diagnosis and result in better therapeutic outcomes of MP pneumonia in children.

Purpose : This study was performed to investigate the epidemiology of enterovirus (EV) infections in children at a secondary hospital during recent 5 years. Methods : We collected the cerebrospinal fluid, stool and throat swab samples from the pediatric patients with suspected EV infections in KEPCO Medical Center, Seoul, Korea from July 2006 to September 2010. EV detection and genotype identification were performed by RT-PCR at Korea Centers for Disease Control and Prevention. Results : A total of 386 samples were collected from 277 patients during study period. Ninety-eight patients (35.4%) were diagnosed with EV infections. The RT-PCR positive rate was the highest in throat swab samples (48.3%). The median age of patient was 4.7 years (range, 0.1-12.5 years). Aseptic meningitis (50, 51.0%) was the most common clinical manifestation; herpangina (22, 22.4%) and hand-foot-mouth disease (18, 18.4%). One hundred EVs were isolated from 98 patients and 20 genotypes of EV were identified; Echovirus 30 (28 cases, 28%), Enterovirus 71 (12 cases, 12%), Echovirus 25 (10 cases, 10%), Echovirus 9 (9 cases, 9%) and Coxsackievirus A6 (8 cases, 8%). Aseptic meningitis caused by Echovirus 30 was the most common manifestation in 2008. There was no complicated case caused by Enterovirus 71. Conclusion : This study showed the epidemiology of confirmed EV infection in children from 2006 to 2010. There is a need for continuous surveillance of EV infections and its clinical manifestations.

Purpose: This retrospective study was performed to identify the clinical characteristics of influenza B infection and compare to influenza A infection. Methods: Medical records of patients diagnosed with influenza using a multiplex PCR test, admitted to Seoul St. Mary's Hospital, during the 2011-2012 influenza season were analyzed. Clinical and laboratory characteristics of influenza B patients were investigated and compared with those of influenza A patients. Results: A total of 145 influenza patients were enrolled during this study period. Among these, 66 and 78 patients were diagnosed with influenza A and B, respectively, and 1 patient was diagnosed with co-existing influenza A and B. Cough (88.2%), rhinorrhea (77.1%) and sputum (60.4%) were the most common symptoms among these influenza patients, and most were diagnosed with upper respiratory infection (31.9%) or lower respiratory infection (49.3%). In comparison to influenza A patients, influenza B patients were older ( years vs. years, P=0.016), and the number of fever days before hospitalization were longer (3.0 days vs. 2.5 days, P=0.043). While sore throat (10.3% vs. 1.5%, P=0.039) and vomiting (20.5% vs. 6.1%, P=0.012) were more common in influenza B patients than in influenza A patients, other clinical and laboratory characteristics were not significantly different between the two groups. Conclusions: No significant differences in clinical and laboratory perspectives were manifested in influenza A and B infections. Preventive measures should be emphasized over treatment in influenza B due to prolonged fever duration before admission.

Dengue fever is an important health problem for international travelers to all endemic areas. The steadily increasing numbers of tourists visiting endemic areas raise the risk of exposure, and imported dengue cases are increasingly observed in nonendemic area. Dengue has a wide spectrum of clinical presentations, often with unpredictable clinical evolution and outcome. While most patients recover following a self-limiting, non-severe clinical course, a small proportion progress to severe disease such as dengue hemorrhagic fever or dengue shock syndrome. Therefore, it is important to suspect dengue fever in every febrile patient returning from the tropics. Whenever it is suspected, a quick diagnosis and adequate managements are essential to avoid complications. We report two cases of imported dengue fever in Korean children presenting with fever, headache, nausea, and rash.